A 14-year-old boy is brought to the office due to right groin pain. Three months ago, the patient developed intermittent right groin pain while playing soccer. Despite stretching exercises, the pain worsened. In the past 4 weeks, he developed a limp and has had difficulty climbing stairs at home. The patient has had no fever, night sweats, or weight loss; there has been no trauma. Vital signs are normal. Height and weight have been tracking along the 75th and 10th percentiles, respectively. On examination, mild atrophy of the right quadriceps and gluteal muscles is present. When the patient stands with the feet together, the right foot points outward and the left foot points straight ahead. When he stands on the right leg, the left half of the pelvis drops downward. When he stands on the left leg, the pelvis remains level. Knees have full range of active motion. Strength on knee extension is 5/5 on the left and 4/5 on the right. Sensation in both legs is intact. Which of the following is the best next step in management of this patient?
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This adolescent with right groin pain has a Trendelenburg sign, a drooping of the contralateral pelvis that occurs when standing on the affected leg. The associated Trendelenburg gait, often described by patients as a limp, is caused by compensatory shifting of the trunk to maintain balance during ambulation. These findings are nonspecific and represent gluteal muscle weakness.
In this patient, the most likely cause is slipped capital femoral epiphysis (SCFE), or slippage of the femoral head from the femoral neck through the growth plate. SCFE classically presents in adolescence with chronic, progressive pain of the hip, groin, or knee. Examination shows decreased abduction and internal rotation of the hip, as seen by this patient's externally rotated foot. Although it is most common in obese children, SCFE can occur with no risk factors, and atrophy of the quadriceps and gluteus muscles due to chronic disuse may be easier to visualize in children with a lower BMI, as in this patient.
The first step in evaluation of suspected SCFE is hip x-rays, which should be bilateral because the contralateral hip may also be affected. Posterior displacement of the epiphysis from the metaphysis confirms the diagnosis. Other suspected conditions causing a Trendelenburg sign (eg, developmental dysplasia of hip, avascular necrosis of femoral head) also warrant bilateral hip x-rays.
(Choice B) A tumor compressing distal spinal nerve roots can lead to gluteal muscle weakness and a Trendelenburg gait, warranting MRI of the lumbosacral spine. However, nocturnal, radiating back pain and sensory changes (eg, numbness, tingling) would be expected.
(Choice C) Nerve conduction studies can evaluate for a superior gluteal nerve injury leading to muscle weakness and atrophy with a Trendelenburg gait. However, this condition typically occurs after gluteal injection or hip fracture/replacement, neither of which is seen here. Moreover, buttock pain, rather than groin pain, is typical.
(Choices D and E) Myopathy can lead to proximal muscle weakness and may warrant evaluation with a creatine kinase level (eg, Becker muscular dystrophy) or skeletal muscle biopsy (eg, polymyositis). However, symptoms would be symmetric and bilateral, resulting in a waddling, rather than Trendelenburg, gait.
Educational objective:
Trendelenburg sign is a nonspecific finding of gluteal muscle weakness marked by drooping of the contralateral pelvis. Slipped capital femoral epiphysis should be suspected in adolescents who also have chronic hip, knee, or groin pain; limited hip abduction and internal rotation; and/or proximal lower extremity muscle atrophy.